Switch construction



INVENTOR. 0 flu/5 W O SCHULTZ SWITCH CONSTRUCTION May 29, 1951 FlledSept 16, 1948 y 29, 1951 w. o. SCHULTZ 2,555,251

SWITCH CONSTRUCTION I Filed Sept. 16. 1948 2 Sheets-Sheet 2 5 9 I f I 2KW "Q 5 wine;

Patented May 29, 1951 SWITCH CONSTRUCTION William O. Schultz, SouthMilwaukee, Wis., assignor to McGraw Electric Company, a corporation ofDelaware Application September 16, 1948, Serial No. 49,512

1 Claim. 1

This invention relates to switch constructions and is an improvementover that shown in the patent to Steinmayer, No. 1,770,953 of July 22,1930, for Switch and Operating Mechanism Therefor, assigned to the sameassignee as this application.

In switch constructions, as previously made, particularly Where theswitch was at times required to carry a heavy current, it has been foundthat the magnetic forces acting on the movable bar or equivalent memberof the switch, acts in a manner tending to, force the movable bar awayfrom the stationary contacts and thus, due to the slight amount of yieldor slack in the opera-ting. mechanism holding the bar in place, causesthe bar to move away a slight amount from the stationary contacts andthus causes pitting of the movable bar or movable contact and thestationary contacts.

Further than this, in previous switch constructions, the force due tothe contact pressure was usually transmitted directly to the connectingrod or actuating rod which moved the connecting bar into and out ofengagement with the stationary contact and consequently where it was.desired to have heavy contact pressure, it usually was accompanied by aheavy strain placed on the connecting link or operating memher.

This invention is designed to overcome the above noted defects andobjects of this invention are to provide a novel form of switch which isdesigned to carry heavy currents, in fact, which is designed to carryexceeding heavy currents for short intervals of time, for instance,surge currents of many thousandths of amperes without disengaging themovable contact members from the stationary contacts and without anypitting or burning whatsoever of either the stationary contacts or themovable contacts.

Further objects are to provide a switch construction which has very highcontact pressure and yet which is so made that the force producing theheavy contact pressure is not directly transmitted to the connecting rodor connecting rods, but is much reduced at the connecting rod so thatthey are not appreciably or materially strained, although this heavycontact pressure is obtained.

Further objects are to provide a novel construction of movable contactand of coacting stationary contacts whereby a rigid, V-shaped stationarycontact can be employed and will coact with a tubular and transverselyyielding movable contact bar, the side walls of which fit Within andcontact the side walls of the V- notches of the stationary contacts andyield and thereby maintain a heavy contact pressure, although there maybe a slight downward motion of the contact bar in a direction away fromthe stationary contacts under very severe overload conditions.

Embodiments of the invention are shown in the accompanying drawings, inwhich:

Figure 1 is a transverse view with most of the parts in section showingthe switch in closed position.

Figure 2 is a side elevation part-1y broken away and partly in sectionshowing the construction of Figure 1.

Figure 3 is an enlarged fragmentary view showing the movable contact baror movable contact of Figures 1 and 2.

Figure 4 is a bottom view of the structure shown in Figure 3, with partsbroken away.

Figure 5 is a view corresponding to Figure 4 of a modified form of theinvention.

Figure 6 is a line section on the line 6-5 of Figure 3.

Figure 7 is a line section on the line 1-4 of Figure 3.

Figure 8 is an end view of one of the stationary contact members and theadjacent portion of the movable contact bar with the remaining portionsof the apparatus omitted.

Figure 9 is a fragmentary view showing the lower portion of theconnecting link or operat" ing link, such view showing in dotted linesthe outline of the movable contact bar.

Referring to the drawings, it will be seen that the switch chosen forillustration is a three phase oil switch. It is equipped with a lowertank I which may be lined with wood or other insulation 2 and whichcontains oil to approximately the level indicated by the referencecharacter 3. The tank I has bolted thereto an intermediate or headportion 4 and the intermediate or head portion 4 has a cover 5 boltedthereto. Suitable gaskets are provdied as indicated and any suitablemeans for holding the three main portions of the switch together may beemployed. It is preferable to provide supporting brackets 6 integralwith the head or intermediate portion 4 so that the switch may beattached to a suitable support in the customary manner. It is to beunderstood that if desired insulating barriers may be interposed betweenthe several sections of the switch as shown,

' for instance, in the above noted patent, and it is also clear that thesame construction herein- 3 after described could be employed for asingle phase switch if so desired.

The switch is provided with an operating or rock shaft 1 carried insuitable bearings and extending outwardly from the head portion 4 andprovided with an operating handle 8. A plurality of crank arms 9 arerigidly carried by the rock shaft 1 and are connected to spaced bracketsH] secured to channel-shaped cross-head H by connecting links 9. Thiscross-head H is uided in any suitable manner, not shown, for example asindicated in the above noted patent. The cross-head is arranged tosimultaneously actuate and impart a vertically reciprocatory motion to aplurality of insulatin connecting links or operating links I2. It ispreferable to provide straps of generally inverted U-shape as indicatedat IS in Figure 1 at the upper end of connecting links 12. These stripsl3 are apertured and receive threaded stems or bolts l4 rigidly carriedby the cross-head H and upper and lower lock nuts I5 are provided onopposite sides of the bite portion or horizontal portion of the U-shapedmembers 13 so that each individual connecting or operating link l2 maybe separately adjusted for a purpose hereinafter to appear.

The stationary contacts are indicated by the reference character l6 andwill be described in greater detail hereinafter. They are rigidlysupported by means of insulating bushings l1 and extend throughinsulating sleeves l8, which bushings and sleeves are located onopposite sides of and secured to a transverse partition or horizontalwall l9 secured to the head 4 as shown most clearly in Figure 1. Thepartition I9 is suitably apertured and forms a guide for theintermediate portion of the connecting links l2, for instance as hasbeen disclosed in the above noted patent. The stationary contacts l6 areconnected to external terminals, not shown, which are located in theinsulating bushings 20, by means of conductors or conducting portions 2|bolted as shown to the upper end of the conducting stems 22 of thestationary contacts l6. Suitable insulating hoods 23 are positioned overthe exposed members 2| and 22 to thus insure adequate insulation orelectrical separation between adjacent portions of the switch in theupper portion of the structure.

The movable contacts or movable bars are inr dicated generally by thereference character 24 and are carried by the connecting links [2 in amanner to permit a slight movement of the movable contacts 24 withreference to the connecting links l2 so as to allow free seating andadjustment of the movable contacts 24 with reference to the stationarycontacts 16 when the switch is closed. It is to be noted at this pointalso that when the switch is closed, that the connecting links 9 and theoperating crank arms 9 form, in effect, toggle link mechanisms and moveslightly past dead center until arrested by a suitable stop as set forthin the above noted patent, when the switch is in fully closed positionto thereby securely lock the switch closed until released and opened bymanipulation of the operating handle 8.

A simple way of connecting the movable contacts 24 to the insulatingconnecting links I2 is by means of a pair of angular brackets 25 securedto the lower ends of each of the links l2 and connected to thecorresponding movable contacts 24 by means of pins 26 extending throughdownward extensions of the brackets 25. Figure 7 shows the general shapeof the brackets 25 and it will be seen from reference to Figure 9 that rconstruction is shown in Figure 5.

each of the brackets 25 is provided with a circular cutaway portion 21within which the corresponding movable contact 24 is loosely positioned.This contact 24 has a very slight motion permitted it about the pivotpin 26 but nevertheless is held substantially horizontal by coactionwith the curved portions or cutaway portions 21 of the brackets 25.

Referring in detail to Figures 3, 4, and 6, it will be seen that themovable contacts 24 are tubular and are formed of two half sections 24'which are spaced apart to provide a slot 28 extending from one end tothe other of the tubular, metal movable contact members 24. A pair ofrings 29 surround intermediate portions of the tubular contact bar 24and are provided with rivets 30 which extend loosely through the twohalf sections 24 of the movable contact bar 24 as shown in Figure 6.These rings limit outward expansion or separation of the two halfsections 24' of the tubular contact bar 24. The two half sections areurged apart by springs 3| located adjacent opposite ends of the members24 and positioned within such members. These springs are provided with acoiled portion 32 and with outward- 1y turned fingers or ears 33 whichloosely fit within apertures 34 formed in the half sections 24 of thecontact bars. These springs will hold themselves in a horizontal planedue to the fact that they can secure their greatest expansion orseparation of their arms when in this position. They are so made thatthey exert a heavy force urging the two half sections 24' of the movablecontact bars 24 apart.

The stationary contacts l6 are provided with V-shaped notches orinternal slanting faces 35, see Figure 8, within which the contact bars24 are drawn when the switch is in closed position as shown in Figure 8.

It will be seen from an examination of this figure that the two halfsections 24 of the contact bars 24 have been forced towards each otheragainst the opposition of the heavy springs 3|. However, in View of thecam action of the slanting faces of the V-shaped notches in thestationary contacts l6, very little resultant force is transmitted tothe connecting or operating links [2.

It is obvious that the movable contacts may be formed of sufficientlyresilient material so that their own resiliency may be relied upon toprovide the necessary yield or inward motion of their end portions whenthey are drawn into the V-shaped notches of the stationary contacts.This form of The movable contact bars are tubular and are indicated bythe reference character 36 and are provided with slots 31 cut inwardlyfrom their ends but leaving the center or intermediate portion of thetubular contact bars 36 intact. These contact bars 36 are secured inidentically the same manner to the operating or connecting links I 2 aspreviously described. In this last form of the invention it is obviousthat when the switch is in closed position and the tubular movablecontact bars 36 are drawn upwardly into the V-shaped notches 35 of thestationary contacts l6, that the end portions of these contact bars willbe forced towards each other and will thus exert a heavy contactpressure against the side walls of the V-shaped notches of thestationary contacts.

It has been found that even with a very heavy overload or short-circuitcurrent that there is no pitting of the stationary contacts or of themovable contacts. Any yield or slackness in the operating mechanismwhich would permit a slight downward motion of the movable contacts withreference to the stationary contacts is compensated for by means of theyielding movable, tubular contacts whose half sections are soconstructed and arranged that that portion thereof which engages thestationary contacts, in both forms of the invention, will maintain aheavy contact pressure with the side walls of the V-shaped notches ofthe stationary contacts although the movable contact bars 24 or 36 mayhave been displaced downwardly a slight amount due to the magneticeifect of the heavy overload current.

If desired, any suitable type of arcing springs or members, forinstance, as indicated at 38 may be employed, although these form nopart of this invention.

It is to be noted that the collars 29 limit the outward motion orseparating motion of the half sections of the contact bar shown inFigures 3 and 4, and that the rivets 30 constitute guides for guidingand holding the two half sections of the bar in alignment with eachother.

It is to be noted that the half sections of the bridging bar, see Figure4, are rigid. Their tubular shape contributes to their rigidity. Inspite of their being rigid and in spite of their having solely lateralmotion of translation, as distinguished from bending, nevertheless theymaintain firm contact with the slanting faces of the stationary contactsand the yielding of the springs allows the half sections to adjustthemselves accurately to the slanting faces of the stationary contacts.

It is to be noted also that in both forms of the invention the contactbar has two spaced end portions with a slot between, whether these endportions are separate members from each other as in Figure 3 and 4, orwhether they are integrally joined adjacent the central portion of thecontact bar as in Figure 5.

Also it is to bev noted that in both forms of the invention the halfsections or spaced end portions are spring urged laterally whetherthrough the medium of separate spring means or due to the resiliency ofthe tubular contact bar itself and are arranged to maintain firmengagement with the spaced surfaces of the stationary contacts.

It is to be noted that in both forms of the invention the contact bar ormovable contact is, in reality, a bridging bar and bridges thestationary contacts.

It will be seen that a very serviceable and simple type of switchconstruction has been provided wherein a heavy contact pressure imaintained, although the switch may be heavily overloaded as duringshort-circuit conditions, for instance, and it will be seen further thatthis heavy contact pressure is obtained without unduly straining orstressing the connecting links or operating members.

Although this invention has been described in considerable detail, it isto be understood that such description is intended as illustrativerather than limiting, as the invention may be variously embodied and isto be interpreted as claimed.

I claim:

An electric switch comprising a pair of spaced stationary contactsprovided with notches having slanting sides, a movable tubular bridgingbar formed of half sections spaced apart by a longitudinal slot, springswithin the end portions of said bridging bar for urging said endportions apart into engagement with the slanting sides of the notches ofsaid stationary contacts when said switch is closed, each of said halfsections being rigid and having lateral motion of translation, spacedcollars surrounding the half sections of said bridging bar and limitingthe amount of separation of the half sections when said switch is open,guiding means carried by said collars and slidably supporting said halfsections and maintaining alignment of the half sections of said bridgingbar, and operating mechanism for moving said bridging bar into switchopen and switch closed positions, said operating mechanism beingpivotally joined to said bridging bar intermediate the ends of saidbridging bar.

WILLIAM O. SCHULTZ.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,808,570 Powers June 2, 19312,099,607 Huttinger Nov. 16, 1937 FOREIGN PATENTS Number Country Date506,293 Great Britain May 25, 1939 643,542 Germany Apr. 10, 1937

